apps/mobile/lib/supabase.ts imports '@chat-app/shared/supabase'. The
shared package declares this subpath in its package.json "exports"
map. The dev Metro resolver respected it; the eager exporter used by
preview/production builds defaulted to legacy resolution and 404'd on
the subpath.
unstable_enablePackageExports=true makes Metro use Node's modern
exports-aware resolver in both modes. Despite the 'unstable_' prefix,
it's the recommended setting in Expo SDK 52 monorepos.